linux-kernel - Re: [syzbot] [bcachefs?] kernel BUG in bch2_inode_update_after

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Message-ID: <680ad54d.050a0220.2c0118.0c70.GAE@google.com>
Date: Thu, 24 Apr 2025 17:20:29 -0700
From: syzbot <syzbot+af878a66b6ed801e9515@...kaller.appspotmail.com>
To: kent.overstreet@...ux.dev, linux-bcachefs@...r.kernel.org, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [bcachefs?] kernel BUG in bch2_inode_update_after_write (2)

syzbot has found a reproducer for the following issue on:

HEAD commit:    e72e9e693307 Merge tag 'net-6.15-rc4' of git://git.kernel...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12d62574580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4f9c44a22d09fd53
dashboard link: https://syzkaller.appspot.com/bug?extid=af878a66b6ed801e9515
compiler:       Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13de9574580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=100fbfcf980000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-e72e9e69.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2bee8b8591c3/vmlinux-e72e9e69.xz
kernel image: https://storage.googleapis.com/syzbot-assets/97a6564905c3/bzImage-e72e9e69.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/f6755d6568aa/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+af878a66b6ed801e9515@...kaller.appspotmail.com

bcachefs (loop0): dirent to missing inode:
  u64s 7 type dirent 4096:189491840996961599:U32_MAX len 0 ver 0: file0 -> 4098 type dir
  
------------[ cut here ]------------
kernel BUG at fs/bcachefs/fs.c:61!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5307 Comm: syz-executor242 Not tainted 6.15.0-rc3-syzkaller-00076-ge72e9e693307 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:bch2_inode_update_after_write+0xac0/0xad0 fs/bcachefs/fs.c:61
Code: 48 89 df 49 89 df 48 89 d3 49 89 c6 e8 a9 83 f0 fd 4c 89 f0 4c 8b 74 24 18 48 89 da 4c 89 fb e9 7a fc ff ff e8 71 8e 8e fd 90 <0f> 0b 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90
RSP: 0018:ffffc9000d4bf940 EFLAGS: 00010293
RAX: ffffffff84313f0f RBX: 1ffff92001a97f34 RCX: ffff888000b68000
RDX: 0000000000000000 RSI: 0000000000001005 RDI: 0000000000001002
RBP: ffffc9000d4bfa70 R08: 0000000000001000 R09: 00000000ffffffff
R10: 0000000000001000 R11: 00000000ffffffff R12: dffffc0000000000
R13: ffff8880119e0000 R14: 0000000000001005 R15: 0000000000001002
FS:  000055558e7f7380(0000) GS:ffff88808d2a3000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007feb125c0100 CR3: 00000000441b8000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __bch2_unlink+0x428/0x4c0 fs/bcachefs/fs.c:818
 bch2_unlink+0xb1/0xf0 fs/bcachefs/fs.c:841
 vfs_unlink+0x391/0x650 fs/namei.c:4579
 do_unlinkat+0x350/0x560 fs/namei.c:4643
 __do_sys_unlink fs/namei.c:4689 [inline]
 __se_sys_unlink fs/namei.c:4687 [inline]
 __x64_sys_unlink+0x47/0x50 fs/namei.c:4687
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7feb12543c99
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffcf96100b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007feb12543c99
RDX: 00007feb12543c99 RSI: 0000000000000000 RDI: 0000200000000500
RBP: 0030656c69662f2e R08: 000055558e7f84c0 R09: 000055558e7f84c0
R10: 000055558e7f84c0 R11: 0000000000000246 R12: 00007ffcf96100e0
R13: 00007ffcf9610308 R14: 431bde82d7b634db R15: 00007feb1258c03b
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:bch2_inode_update_after_write+0xac0/0xad0 fs/bcachefs/fs.c:61
Code: 48 89 df 49 89 df 48 89 d3 49 89 c6 e8 a9 83 f0 fd 4c 89 f0 4c 8b 74 24 18 48 89 da 4c 89 fb e9 7a fc ff ff e8 71 8e 8e fd 90 <0f> 0b 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90
RSP: 0018:ffffc9000d4bf940 EFLAGS: 00010293
RAX: ffffffff84313f0f RBX: 1ffff92001a97f34 RCX: ffff888000b68000
RDX: 0000000000000000 RSI: 0000000000001005 RDI: 0000000000001002
RBP: ffffc9000d4bfa70 R08: 0000000000001000 R09: 00000000ffffffff
R10: 0000000000001000 R11: 00000000ffffffff R12: dffffc0000000000
R13: ffff8880119e0000 R14: 0000000000001005 R15: 0000000000001002
FS:  000055558e7f7380(0000) GS:ffff88808d2a3000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007feb125c0100 CR3: 00000000441b8000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.